Commutator cleaner for electric motors



March 16, 1937. G H, CALEY 2,073,830

COMMUTATOR CLEANER FOR ELECTRIC MOTORS Filed June 11, 1956 J8 InJentSEPatented Mar. 16, 1937 UNITED STATES PATENT OFFICE COMIVIUTATOR CLEANERFOR ELECTRIC MOTORS Application June 11,

6 Claims.

The present invention relates to commutator cleaners for electric motorsand the main object of the invention is to provide a cleaner of thistype which shall be simple in construction, economical to manufactureand highly efiicient in operation. Another object is to provide acleaner which will always be in proper position with its cleaningelement held tight against the commutator surface and properly centeredupon it. An-

other object is to produce a new device with a minimum of parts and toassociate them with the commutator in such a way that the device may beenclosed with the commutator within the usual motor casing. Anotherobject is to arrange the parts so they are easily accessible and may bereadily replaced when desired.

The various features and advantages of the invention will be bestunderstood upon reference to the following description taken inconnection with the accompanying drawing wherein a preferred embodimentof the invention is disclosed. The scope of the invention isparticularly pointed out in the appended claims.

In said drawing, Fig. 1 is an end elevation of an electric motorprovided with a commutator cleaner constructed and arranged inaccordance with the present invention, some of the parts being shown insection taken on a plane indicated by the line l-l of Fig. 2; Fig. 2 isa partial sectional View of a portion of the same motor, the plane ofsection being indicated by the line 2-2 of Fig. 1; Figs. 3 and 4 areperspective views of the cleaner removed from the motor, the same beingviewed in different directions in the two figures; Fig. 5 is a plan viewof the cleaner pad before being placed in curved position upon itssupporting block; and Fig. 6 is a transverse section through the blockand pad illustrating a preferred way of securing the pad to the block,

a tenon on the pad being shown in position to be pressed into acooperating mortise in one side of the block. Throughout these viewslike characters refer to like parts.

It is well known that in the operation of electric motors, particularlyin the railway signaling field, it is important to keep the commutatorsclean in order that the signals may not fail to function. Motors in suchservice are ex- 50 posed to the hazards of the accumulations of dirt,frost, oil in congealed form, and other foreign matters that accumulateupon the surface of the commutator at different seasons of the year andunder different conditions of service. By use 55 of the commutatorcleaner constructed and ar- 1936, Serial No. 84,746

ranged in accordance with the present invention the surface of thecommutator is kept clean.

Referring to the drawing in detail, A designates a typical switch motorof a type commonly employed in railway signaling. In this motor thearmature axis is usually horizontally arranged and the motor itselfincludes the frame It), the usual field windings ll, armature windingsl2, commutator I3, brushes l4 and brush holders l5 and I5a. These motorparts are well known and need not be further described except as thedescription incident to the construction and operation of the cleanermay bring them into view. In the present instance the main frame [0carries an auxiliary frame [6 which has a base portion in the form of aring I! and an end bearing l8 connected thereto by a plurality of armsl9. The outer end of the bearing 18 terminates in a threaded stud 2|).Suitable bolts 2| passing through the annular flange of the ring I! intothe adjacent portion of the main frame In serve to hold the frame partstogether. These bolts may be screwed home after the armature has beenproperly assembled with its shaft 22 properly positioned in its bearingsas will be obvious.

The brush holders l5 and 15a are suitably connected to the frame l6 bymeans of screws 23 which pass through suitable openings in the brushholders and into threaded engagement with threaded openings in theadjacent flange of the o ring l6. Each of the brush holders is providedwith a coiled spring 24 which serves to press the brushes [4 intoengagement with the commutator l3. In the present instance each spring24 is held in place by a screw 25. Other screws 26 are threaded throughthreaded openings in the body of each brush holder and are pressed intoholding engagement with the associated brush I4. Thus the brushes areheld in set position. The manner of supporting the brush holders istypical and may be varied according to circumstances.

No distinction has been made in the description between the two brushholders l5 and l5a but it should be noted that they are reversed, theone being, so to speak, a right hand holder and the other a left handholder.

Electrical connection is established with the brush holders through theterminal screws 30 upon which are the knurled nuts 3!. These screws aresuitably supported upon and insulated from the supporting frame. Theparticular motor illustrated is also provided with a glass bell or cover32 which has a central opening through which the stud 20 may be passed.The

open end of the bell has its periphery fitted against the adjacentportion of the ring IS with a suitable washer 33 intervening. A thumbnut 34 screwed upon the stud 2i] presses the bell mouth against thewasher 33 and provides a tight closure to protect the inclosedcommutator and associated parts.

The cleaner is in itself very simple in construction. It comprises, inthe embodiment shown, a resilient leaf-like metal strip 37 inassociation with an insulating block 38 and the cleaning pad 39. The padhas a dimension in the direction of the axis of rotation of thecommutator which closely approaches the Width of, the commutator. Thispad is made of flexible resilient material such as felt and it is reliedupon to wipe ofi the accumulations upon the surface of the commutator asthe latter engages it when rotating. Obviously, the material out ofwhich the pad is made may be varied and it is also clear that thedimensions themselves may be changed to suit particular conditions.

The block 38 is composed of insulating material and is preferably atruncated pyramid in form. The under surface of the block is concave andcylindrical to conform to the curvature of the commutator. When the pad39 is in place it fits up snugly against the curved bottom of the block38 and this curvature is such that the lower portion of the pad thennicely fits against the curved surface of the commutator.

There are many ways in which the pad may be secured to the block 38. Inthe present instance the edge of the block 38 which, when the motor isoperating, lies toward the oncoming commutator bars is provided with anotch or mortise 46; Preferably this mortise is dovetailed in shape. Thepart of the pad which fits into this mortise is the tongue or tenon 4!.This tenon may be variously formed. In the instance illustrated thepiece of material out of which the pad 39 is made is provided with aslit or cut 42 associated with two angular cuts 43, as clearly shown inFig. 5. These cuts preferably extend all the way through the material,as indicated by the separated pad and tenon shown in'Fig. 6. When thetenon is drawn up in this way it may be easily slipped into place in themortise 4G. The movement of the commutator is in the direction indicatedby the arrow in Fig. 1i. In other words, it is in a direction such thatthe commutator bars first encounter the pad at the edge adjacent to thetenon 4|. The resulting forces are thus such as to hold the pad inplace. Any tendency to drag the pad away is opposed by the inclinededges of the dovetailed tenon engaging the like edges of the mortise. Inother words, the force applied tends to wedge the tenon more securely inthe mortise. Obviously, too, the pad might be otherwise secured to theblock. Thus, it might be glued to it.

The strip 31 is secured at its inner end to the top face of the block 38by a pin or rivet M. The opposite or outer end of the strip 3? isbifurcated and terminates in two arms 4'! which are spaced so as to givean intermediate space or slot 58. It will be noted that the plane of thearms 4'Iis substantially at right angles to the general direction of themain portion of the strip 37. The end 49, where the pin M is located, isflat and engages the fiat top of the block 38. Adjacent to the fiatportion 49 is an angular portion 59 which turns abruptly away from theplane of the portion 49 with what is practically aright-angled turn. Thestrip 37, adjacent t0 the abruptly turned portion 50, again takes alongitudinal direction in the portion 5| which also is slightly curved,as clearly shown.

It will be noted that when the cleaner shown in perspective in Figures 3and 4 is placed on the motor, the arms 41 at the bifurcated end willpass down upon opposite sides of the stud 20. In other words, the stud2?] will enter the space 48. In assembling the parts, a nut 52 isthreaded upon the stud 2i] and screwed down so as to apply pressureagainst the end of the bearing 18. A washer 53 may be employed betweenthe nut 52 and the end of the bearing. By using more than one washer 53it is possible to change the position of the arms 47 lengthwise of thestud 20, the greater the number of washers the greater the distance ofthe bifurcated arms 47 from the commutator. The same result may be hadby replacing the nut 52 by one or more nuts providing a differentresultant thickness. When the arms 4 are once properly positioned alongthe stud by the proper number of nuts or washers as just stated, then,withthe arms 41 straddling the stud 20, it is only necessary to applyanother nut 54 to the stud 20 and screw it home tight against the arms4'! of the strip. When this is done the position of the pad 39 in thedirection of the aixs of the commutator and armature will be determined.Furthermore, the material of the'strip 3'! is in itself, although aspring material, of sufiicient pliability so that the strip may be benta little so as to vary this adjustment in the direction of said axiseven without changing the setting of the arms 41 by the use of nuts andwashers as just described.

Because of the resiliency of the metal of the strip 37 there will be,when the bifurcated end is held in place upon the stud 20, a certainamount of pressure applied to the block 38 and the pad 38 beneath it.This pressure may be varied by the setting of the stud within the space48. If the setting be such that the stud is near the inner end of thespace then, obviously, other things being equal, the pressure would begreater than it would be were the position of the stud nearer the openend of the slot 48 As before, quite independently of this'setting of thebifurcated end of the strip, it is also possible to bend the strip 31 soas to increase or decrease the pressure of the pad upon the commutator.

It will also be apparent that by loosening up the nut 54 the strip 31may be rotated about the axis of rotation of the armature and thus thepad may be annularly displaced so as to occupy any desired position,within the range of move,- ment possible, upon the commutator. ,Oncethus located, it is only necessary to again screw down the nut 54.

In carrying out my invention it will be clear that some changes may bemade in the details of the parts without departing from the spirit andscope of the invention. I therefore do not wish to be limited to thedetails shown but aim to cover by the terms of the appended claims allthose alterations and modifications which rightly come within the spiritand scope of my invention.

I claim:

1. The combination with the frame and commutator of an electric motor,of a cleaning pad for engaging said commutator, means for yieldinglypressing said pad radially toward the axis of rotation of saidcommutator, and securing means for connecting said pressing means tosaid 1 a in frame, said securing means being operative to engage saidpressing means to give different radial adjustments of said pressingmeans thereby to vary the pressure of said pad on said commutator, andfurther operative to permit rotation of said pressing means about saidaxis of rotation thereby to permit adjustment of said padcircumferentially of said commutator.

2. The combination with the frame and commutator of an electric motor,of a cleaning pad for engaging said commutator, an insulating blockengaging the outer surface of said pad, and a resilient leaf-like metalstrip secured at one end to said block and extending generally in thedirection of the commutator axis, a threaded stud projecting from saidframe outward in said axis, the outer end of said strip being bifurcatedto embrace said stud, and means for clamping the outer end of said stripupon said stud in different radial positions relative to said axis andin different angular positions about said axis, whereby the resilientaction of said strip on said block and pad may be varied and thecircumferential position of said pad on said commutator may be varied.

'3. The combination with the frame and commutator of an electric motor,of a cleaning pad for engaging said commutator, an insulating blockengaging the outer surface of said pad, and a resilient leaf-like metalstrip secured at one end to said block and extending generally in thedirection of the commutator axis, a threaded stud projecting from saidframe outward in said axis, the outer end of said strip being bifurcatedto embrace said stud, and means for clamping the outer end of said stripupon said stud in different radial positions relative to said axis, indifferent angular positions about said axis and in differentlongitudinal positions on said stud, whereby the resilient action ofsaid strip on said block and pad may be varied, the circumferentialposition of said pad on said commutator may be varied, and thetransverse position of said pad on said commutator relative to a centralplane at right angles to said commutator axis may be varied.

4. The combination with the frame of an electric motor, its commutator,a commutator cover, a threaded stud for receiving said cover and a nutfor holding said cover in place, of a cleaning pad for engaging saidcommutator, a resilient leaf-like metal strip supportingly secured tosaid pad and having its outer end apertured for the reception of saidstud, and abutting means on said stud to operatively engage oppositesides of the outer end of said strip to secure the same in differentadjusted positions, said abutting means being independent in operationof said cover and cover holding nut.

5. The combination with the frame and commutator of an electric motor,of a cleaning pad for engaging said commutator, a resilient leaflikemetal strip for supporting said pad from said frame, and means forsecuring said strip to said frame at a point in substantial alinementwith the axis of rotation of said commutator, said means includingclamping members which engage opposite sides of said strip to hold thesame in diiferent rotational positions and also at different distancesfrom said commutator, and the connection of said strip to said pad beingoutward of the commutator surface relative to said axis of rotation,thereby to direct the variable pressures of said strip radially inwardtoward said axis of rotation.

6. The combination with the frame and commutator of an electric motor,of a cleaning pad for engaging said commutator, a resilient leaflikemetal strip for supporting said pad from said frame, and means forsecuring said strip to said frame at a point in substantial alinementwith the axis of rotation of said commutator, said means includingclamping members which engage opposite sides of said strip to hold thesame in different rotational positions and also at different distancesfrom said commutator, and the connection of said strip to said pad beingoutward of the commutator surface relative to said axis of rotation,thereby to direct the variable pressures of said strip radially inwardtoward said axis of rotation, and said strip being pliable enough to beset by bending soas to have diiferent over-all lengths in the directionof said axis of rotation, thereby additionally providing for adjustmentof said pad upon said commutator transversely of its plane of rotation.

GLENN H. CALEY.

